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Out of curiosity, how is the embedded story (for both bare-metal and RTOS) in Rust nowadays? I took a look early last year, and I remember feeling that the ecos

Out of curiosity, how is the embedded story (for both bare-metal and RTOS) in Rust nowadays? I took a look early last year, and I remember feeling that the ecosystem still wasn't as mature as I liked. There's svd2rust [0] and dslite2svd [1], which is basically "bindgen for hardware". Please do correct me if I'm wrong, but from what I understood [2], most SVD files leave out a lot of information so a lot of what svd2rust generates is unsafe. Seems like the only way around that is to patch the SVD files. Is this still the case? In addition, what about compiling with no stdlib? And how does that interop with existing Crates (ie. do new "embedded-specific" Crates need to be created?) Super excited to see Rust gain traction! I'll definitely take another shot in my free time and see how the ecosystem has matured. [0] https://github.com/japaric/svd2rust https://github.com/japaric/svd2rust [1] https://github.com/m-labs/dslite2svd https://github.com/m-labs/dslite2svd [2] https://www.reddit.com/r/rust/comments/687b3l/embedded_in_rust_rust_your_arm_microcontroller/dhby29s/?context=1 https://www.reddit.com/r/rust/comments/687b3l/embedded_in_ru...

jefftime 9y ago
I tried exploring no_std Rust recently, and found it to be quite frustrating. After just using a Result type I was getting errors of things like `eh_unwind_resume` being undefined. Toggling LTO rectified my problems but didn't give me much confidence in reliably using no_std
- red75prime 9y ago
  `-C panic=abort` compiler option should have fixed the problem. If you want to be able to intercept panics, you need to provide implementations for `eh_unwind_resume` and `eh_personality`.
  - jefftime 9y ago
    Perhaps it's just an issue of me not being educated enough with this kind of low-level Rust. Setting panic to abort in the cargo config did indeed fix `eh_personality` being undefined, but `eh_unwind_resume` still seems finnicky. Building in release will work, but building in debug will still complain
    - red75prime 9y ago
      I'm a little rusty on the topic, but it seems ([0]) that adding `#[no_mangle]` before `panic_fmt` should fix it. [0] https://github.com/rust-lang/rust/issues/38281 https://github.com/rust-lang/rust/issues/38281
      - steveklabnik 9y ago
        See also https://doc.rust-lang.org/nightly/unstable-book/language-features/lang-items.html#writing-an-executable-without-stdlib https://doc.rust-lang.org/nightly/unstable-book/language-fea...
        jefftime 9y ago
        Even specifying `eh_unwind_resume` as a lang item gives me a linking error in debug builds.
        steveklabnik 9y ago
        Did you define them exactly the same way? Every aspect has to be identical; extern, no mangle, function name, arguments, lang item. If this happens to be open source, I can take a look at it.
        jefftime 9y ago
        I just whipped this up yesterday to test if I was still having the same issues. Debug fails to build with a linking error "undefined reference to `_Unwind_Resume`". Release build works fine. I'm using rustc 1.25.0-nightly on Ubuntu 17.10 https://gist.github.com/jefftime/d7e96461138b5aa6895550b63caac66c https://gist.github.com/jefftime/d7e96461138b5aa6895550b63ca...
        steveklabnik 9y ago
        The lang item symbol names need to be prefixed with rust_ like this: https://gist.github.com/steveklabnik/5abd59a8fe7e5abda3db58bd8c208fbb https://gist.github.com/steveklabnik/5abd59a8fe7e5abda3db58b...
  - quotemstr 9y ago
    For low level code, do you really want to abort on panic? Rust error handling is easily my least favorite part of the language, combining the disadvantages of exceptions and return codes.
    - steveklabnik 9y ago
      Many do, yes. Panics are non-recoverable errors, and aborting produces leaner code, which is important on embedded.
      - quotemstr 9y ago
        Panics are recoverable though
        steveklabnik 9y ago
        They’re not guaranteed to be, so you can’t rely on it. You can say that you do, but then you may cut yourself off from the rest of the ecosystem. Libraries generally can’t rely on either behavior, applications choose.
        quotemstr 9y ago
        And that's why I think the Rust has a worst-of-both-worlds error handling strategy.

jefftime 9y ago

I tried exploring no_std Rust recently, and found it to be quite frustrating. After just using a Result type I was getting errors of things like `eh_unwind_resume` being undefined. Toggling LTO rectified my problems but didn't give me much confidence in reliably using no_std

red75prime 9y ago
`-C panic=abort` compiler option should have fixed the problem. If you want to be able to intercept panics, you need to provide implementations for `eh_unwind_resume` and `eh_personality`.
- jefftime 9y ago
  Perhaps it's just an issue of me not being educated enough with this kind of low-level Rust. Setting panic to abort in the cargo config did indeed fix `eh_personality` being undefined, but `eh_unwind_resume` still seems finnicky. Building in release will work, but building in debug will still complain
  - red75prime 9y ago
    I'm a little rusty on the topic, but it seems ([0]) that adding `#[no_mangle]` before `panic_fmt` should fix it. [0] https://github.com/rust-lang/rust/issues/38281 https://github.com/rust-lang/rust/issues/38281
    - steveklabnik 9y ago
      See also https://doc.rust-lang.org/nightly/unstable-book/language-features/lang-items.html#writing-an-executable-without-stdlib https://doc.rust-lang.org/nightly/unstable-book/language-fea...
      - jefftime 9y ago
        Even specifying `eh_unwind_resume` as a lang item gives me a linking error in debug builds.
        steveklabnik 9y ago
        Did you define them exactly the same way? Every aspect has to be identical; extern, no mangle, function name, arguments, lang item. If this happens to be open source, I can take a look at it.
        jefftime 9y ago
        I just whipped this up yesterday to test if I was still having the same issues. Debug fails to build with a linking error "undefined reference to `_Unwind_Resume`". Release build works fine. I'm using rustc 1.25.0-nightly on Ubuntu 17.10 https://gist.github.com/jefftime/d7e96461138b5aa6895550b63caac66c https://gist.github.com/jefftime/d7e96461138b5aa6895550b63ca...
        steveklabnik 9y ago
        The lang item symbol names need to be prefixed with rust_ like this: https://gist.github.com/steveklabnik/5abd59a8fe7e5abda3db58bd8c208fbb https://gist.github.com/steveklabnik/5abd59a8fe7e5abda3db58b...
- quotemstr 9y ago
  For low level code, do you really want to abort on panic? Rust error handling is easily my least favorite part of the language, combining the disadvantages of exceptions and return codes.
  - steveklabnik 9y ago
    Many do, yes. Panics are non-recoverable errors, and aborting produces leaner code, which is important on embedded.
    - quotemstr 9y ago
      Panics are recoverable though
      - steveklabnik 9y ago
        They’re not guaranteed to be, so you can’t rely on it. You can say that you do, but then you may cut yourself off from the rest of the ecosystem. Libraries generally can’t rely on either behavior, applications choose.
        quotemstr 9y ago
        And that's why I think the Rust has a worst-of-both-worlds error handling strategy.